Conventionally, a blower which is used in a ceiling-embedded type ventilation fan or the like includes an orifice having a bellmouth-shaped inflow port (see PTL 1, for example). Hereinafter, the blower is described with reference to FIG. 4.
FIG. 4 is a constitutional view showing a cross section of a conventional blower. As shown in FIG. 4, multi-blade blower 110 includes: impeller 113 and bellmouth 112. Multi-blade blower 110 sucks a gas along the direction of axis of rotation O-O, and blows out a fluid in the direction which intersects with axis of rotation O-O. Bellmouth 112 has: suction port 112a disposed so as to face impeller 113; and recessed portion 112d which is indented toward impeller 113 side around suction port 112a and forms a negative pressure space therein. In multi-blade blower 110 having such a configuration, turbulence of the flow of air sucked into an area in the vicinity of suction port 112a is suppressed. Further, in multi-blade blower 110, it is possible to suppress turbulence generated by a circulation flow which is a flow of a gas sucked into impeller 113 again after being blown out from impeller 113 once and hence, a noise is reduced.